The invention relates to a command key such as is found in particular on the keypads of, for example, mobile telephones, and more particularly a command key with integrated illumination comprising a raised pressure and command part, bearing at least one character label, and means of illuminating the character label. In the case of a keypad, it is necessary to consider a plurality of keys rather than a single one.
For the manufacture of a key, the pressure pat may be moulded out of translucent material, then coated with a layer of semi-transparent paint and a layer of opaque paint and finally the character label is produced, for example, by laser etching.
The pressure part may likewise be moulded by twin injection of a material intended to constitute the body of the key and another material intended to produce the character label.
It is also possible to stamp a transparent thermoplastic film upon which the character label is produced by serigraphy using an opaque ink and a semi-transparent ink.
To illuminate the character label, light-emitting diodes (LEDs) are most frequently used, the disadvantage of these being that they consume a lot of electrical energy and, for this reason, reduce the life of the mobile telephone""s battery, to take that example.
In order to resolve this problem, a light-emitting illumination layer may be used. EP 847 066 presents a command key of the type described above, which has a light-emitting illumination layer. However, this light-emitting layer, carried on a substrate which is separate from the pressure and command part, produces inadequate illumination.
DE 26 13 902 likewise presents a switch with a button and, within the latter, a light-emitting illumination layer whose two electrodes are connected to an electrical supply circuit via a spring and a connecting pin. Owing to the position of the layer, the illumination is more effective, but the electrical connectors supplying the layer are cumbersome.
The present invention proposes to provide illumination for a command key using a light-emitting layer, in a neat and effective manner.
To this end, the invention relates to a command key with integrated illumination comprising a raised pressure and command part, bearing at least one character label, and means of illuminating the character label comprising a light-emitting illumination layer, characterised by the fact that the illumination layer extends along the base of the pressure and command part and is continued laterally either by electrical contacts or by electrical connection tracks.
Since the illumination layer extends along the base of the pressure part, it is located in the immediate vicinity of the character label which considerably limits losses in illumination. In addition, the lateral extensions of the illumination layer, via electrical contacts or via conducting tracks, make it possible to take an electrical supply to the illumination layer without adding to the space taken up by the key.
The invention also relates to a process for the manufacture of a key as described above, in which a film is taken, upon which at least one character label is produced by serigraphy; the said film is stamped to form the raised pressure and command part and is characterised by the fact that a light-emitting illumination layer is disposed within the stamped part.
In a particular embodiment, prior to stamping, the illumination layer is deposited onto a zone of the said film, intended to form the base of the stamped part, and the illumination layer is extended laterally by means of electrical conductors.
In another embodiment, another film is taken, onto which is deposited the illumination layer which is laterally extended by means of electrical conductors, a portion of film carrying the illumination layer with an extension supporting the electrical conductors is cut out from the said other film, and the said portion of film is placed inside of the stamped part.
As a result there is no risk of damaging the illumination layer during stamping.
The invention will be more easily understood with the aid of the following description of different embodiments of the key of the invention and of corresponding different embodiments of the manufacturing process for that key, with reference to the appended drawing in which.
FIG. 1 shows a lateral cross-sectional view of the key according to a first embodiment;
FIG. 2 shows a lateral cross-sectional view of an illumination layer for the key in FIG. 1;
FIG. 3 shows a cross-sectional and exploded perspective view of a pressure and command part of the key in FIG. 1;
FIG. 4 shows a cross-sectional and exploded perspective view of a pressure and command part of the key, according to a second embodiment;
FIG. 5 shows a lateral cross-sectional view of the pressure and command part of the key in FIG. 4;
FIG. 6 shows a cross-sectional and exploded perspective view of a pressure and command part of the key according to a third embodiment and
FIG. 7 shows a lateral cross-sectional view of the pressure and command part of the key in FIG. 6.